Current and Potential Zones of Infestation

Current Zones of Infestation

As of September 4, 2002, SOD has been confirmed by laboratory isolation in twelve counties in California, and reported in several others (2). It was first reported in Marin County, California, in 1995. It has been reported in a 190-mile range from Sonoma Valley in the north to Big Sur in the south, as well as east to the Napa County border, approximately 25 miles inland (1). Sudden Oak Death has also been confirmed in 9 isolated spots in southwestern Oregon and is currently considered confined to its original 9-square-mile control area in Curry County (2, 3).

Outside of the United States, SOD has been confirmed in Germany and The Netherlands. There are reports of SOD infection of a limited number of viburnum nursery stock in Great Britain as well. Those plants are said to have been destroyed; and Great Britain is taking measures to prohibit the importation of known host plants, and oak wood, from areas of the US known to be infested with SOD (3).

Potential Zones of Infestation

It is likely that SOD will continue to spread among susceptible species in California and Oregon when not treated. Areas of the US supporting susceptible species and having climates similar to coastal California and Oregon are potentially at risk. A nationwide risk map developed by the US Forest Service places 14 states in two main areas at risk. The first area includes Washington, Oregon, and California. The second area is in the southern Appalachian Mountains including Kentucky, Tennessee, Alabama, Georgia, North and South Carolina, Virginia, Maryland, and West Virginia. Portions of coastal Mississippi and Alabama are also considered high risk. The risk assessment is based on host and climate factors, as well as rhododendron nursery locations (4).

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Last Modified: 11/19/2007